The Lab Window and Diagrams

The Lab is the working place of this project: one window for the configuration and the runs, and one diagram layout that takes any input signal. Open start_lab.sce and press F5.

The window

Part	Controls	What it does
Configuration	Stepper-C library, Browse	Folder of the library, kept for the next starts. OK or the name of the missing file appears next to it
Configuration	ngspice stage, Browse, Use default	The stage file. The line below shows its bus voltage, frequency and number of table points, and warns when the board runs other values
Configuration	Backend	FIXED or FLOAT. One Scilab session links one library, so a change after linking asks for a restart
Model	SIL: C code, MIL: Scilab prototype	Which controller the buttons below use
Model	Scenario	One of the eight ready experiments
Model	Open in Xcos	Opens the scenario as a diagram, from a temporary file
Model	Run	Runs it without windows. The result is in the variable sil, and the status line names the first fault
Model	Report	Draws the last run with sil_report()
Model	Compare MIL / SIL	Runs both and overlays iA, speed and commanded position, with the largest difference up to the first fault
Tests	Group, Run tests, Refresh	Starts tests/run_all.sce in a second Scilab process for All, SIL, MIL or Model. Refresh reads the results so far, FAIL first

The settings are saved per user; see Settings file.

Scenarios

No.	Name	Time	Source	Expected
1	Current step 0.5 → 2 A, rotor locked	0.03 s	Step on the run current at 10 ms	No fault
2	Move 2 revolutions	0.8 s	Position command 6400 microsteps	No fault
3	Velocity step to 1 rev/s	0.4 s	Step on the command at 50 ms	No fault
4	Velocity sine, 1 rev/s, 2 Hz	0.6 s	Sine on the command	No fault
5	Velocity ramp to 5 rev/s	0.5 s	Ramp from 50 ms	No fault
6	Load step 0.25 N·m, below the pull-out torque	0.4 s	Step on the load at 0.2 s, stall detection on	No fault
7	Load step 0.5 N·m, above the pull-out torque	0.4 s	Step on the load at 0.2 s, stall detection on	Stall fault
8	Stall at the hold current, 0.12 N·m	0.62 s	Constant load, 1.5 A run, 0.5 A hold after 0.5 s, stall detection on	Stall fault

Test S10 runs all eight and checks these expectations.

The diagram

xcos/stepper_lab.zcos (SIL) and xcos/stepper_lab_mil.zcos (MIL) have the same four superblocks. Double-click one to open it.

The figure below shows what the superblocks hold and how they connect.

Superblock	Holds	You change
Inputs	Three CONST_m sources: lab_cmd, lab_irun, lab_load	Replace a source with any block of the Xcos palette
Controller	STEPPER_CTRL_IO (SIL) or STEPPER_CTRL_MIL (MIL)	Nothing
Plant	STEPPER_PLANT_IO: power stage, motor and ADC	Nothing; its parameters come from the context
Outputs	STEPPER_MONITOR_IO, five named scopes, and the workspace block writing sil	Scope ranges, through scope_i, scope_rpm, scope_pos

Use your own signal

1. In the window, choose a scenario and press Open in Xcos. This links the library.
2. Open Simulation → Set Context. A scenario adds its own lines at the end of the context, such as T_end, lab_mode or lab_cmd, and these win over the lines above them. Change your values there.
3. Open the superblock Inputs and replace the source with, for example, STEP_FUNCTION, GENSIN_f or RAMP.
4. Press Start. The scopes show the run, and sil holds the results when it ends.

To open xcos/stepper_lab.zcos directly, first run exec("loader.sce", -1); and sil_build("FIXED"); in Scilab. Otherwise the functions of the context and the C blocks are not there, and Start fails.

The three inputs

Input	Unit	Read	Limits
Motion command	Microsteps/s with lab_mode = 1; microsteps with lab_mode = 2; unused with lab_mode = 0	Once per slow period (1 kHz)	Velocity to ±mp.v_max; position to the int32_t range
Run current	A	Once per slow period	1 mA to the smaller of the rated current and the overcurrent trip. The hold current becomes the smaller of hold and run
Load torque	N·m	Input of the plant	None. A value that is not finite keeps the last one, without a flag in column 23

lab_mode	Motion command	Library call in SIL
1	Velocity	sstep_run()
2	Position	sstep_move_to()
0	The table cmds, [t kind value]: 1 MOVE, 2 RUN, 3 STOP	As in the table

Behavior of the command and current inputs:

• A value is rounded and limited. A NaN keeps the last value. In both cases column 23 of sil.values shows the flag for that slow period.
• A new value is applied only when it differs from the last one.
• The motion generator of the library still limits acceleration and speed, so the applied command (column 20) is not the speed of the rotor.
• After a fault the inputs are ignored, the outputs stay off, and the simulation goes on to T_end.

Results

The diagram writes sil.time and sil.values; the columns are in Reference.

res = lab_run("SIL", 7);        // load step above the pull-out torque
d = sil_report_data(res);
mprintf("%s at %.1f ms\n", d.fault_names, d.t_fault * 1e3);

// no-run
sil_report(res);        // opens a figure

sil_report(sil, visible) draws every group with title, unit, legend and grid, and marks the first fault. The vertical scales come from the run up to shortly after the fault, so what follows it does not hide the rest. sil_report_data(sil) gives the same content as data, without graphics.

Common mistakes

Symptom	Cause	What to do
The status asks for the folder of Stepper-C	The library was not found in the search order	Press Browse; the folder must hold sstep.h, inc/sstep_ctrl.h and src/sstep_ctrl.c
"Restart Scilab to use FLOAT"	This session already linked the other backend	Restart Scilab
"Restart Scilab to link the library of the new folder"	The folder changed after linking	Restart Scilab
The speed does not follow a fast command	The motion generator limits it with mp.v_max, mp.acc, mp.dec	Raise these in the context; column 20 shows what was applied
Column 23 is 1	An input is out of range or NaN	See the limits above
MIL outputs stay at zero with state 3 and flag 16	The configuration is one the library refuses, or it asks for voltage drive	Read the printed message; lab_run() raises it as an error
A run in MIL takes long	The prototype is interpreted Scilab: 15 s per simulated second on a 0.15 s run	Use SIL for everyday runs
A selected stage file shows a message and is not used	The file is not valid; the message names the file and the field	Fix the export, or press Use default